Department of Physics, University of Tokyo, Hongo, Tokyo, Japan.
Phys Rev Lett. 2011 Jun 10;106(23):236401. doi: 10.1103/PhysRevLett.106.236401. Epub 2011 Jun 6.
We show theoretically that the sudden application of an appropriate ac field to correlated lattice fermions flips the band structure and effectively switches the interaction from repulsive to attractive. The nonadiabatically driven system is characterized by a negative temperature with a population inversion. We numerically demonstrate the converted interaction in an ac-driven Hubbard model with the nonequilibrium dynamical mean-field theory solved by the continuous-time quantum Monte Carlo method. Based on this, we propose an efficient ramp-up protocol for ac fields that can suppress heating, which leads to an effectively attractive Hubbard model with a temperature below the superconducting transition temperature of the equilibrium system.
我们从理论上表明，突然施加适当的交流场可以翻转关联晶格费米子的能带结构，并有效地将相互作用从排斥变为吸引。非绝热驱动系统的特征是具有反转粒子数的负温度。我们通过连续时间量子蒙特卡罗方法求解的非平衡动力学平均场理论，在交流驱动 Hubbard 模型中数值证明了相互作用的转换。在此基础上，我们提出了一种有效的交流场斜坡上升协议，可以抑制加热，从而导致有效吸引的 Hubbard 模型，其温度低于平衡系统的超导转变温度。
